1,596 research outputs found

    A quantitative central limit theorem for the effective conductance on the discrete torus

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    We study a random conductance problem on a dd-dimensional discrete torus of size L>0L > 0. The conductances are independent, identically distributed random variables uniformly bounded from above and below by positive constants. The effective conductance ALA_L of the network is a random variable, depending on LL, and the main result is a quantitative central limit theorem for this quantity as LL \to \infty. In terms of scalings we prove that this nonlinear nonlocal function ALA_L essentially behaves as if it were a simple spatial average of the conductances (up to logarithmic corrections). The main achievement of this contribution is the precise asymptotic description of the variance of ALA_L.Comment: 37 page

    On Random Field Induced Ordering in the Classical XY Model

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    Consider the classical XY model in a weak random external field pointing along the YY axis with strength ϵ\epsilon. We study the behavior of this model as the range of the interaction is varied. We prove that in any dimension d2d \geq 2 and for all ϵ\epsilon sufficiently small, there is a range L=L(ϵ)L=L(\epsilon) so that whenever the inverse temperature β\beta is larger than some β(ϵ)\beta(\epsilon), there is strong residual ordering along the XX direction.Comment: 30 page

    Geodesics of Random Riemannian Metrics

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    We analyze the disordered Riemannian geometry resulting from random perturbations of the Euclidean metric. We focus on geodesics, the paths traced out by a particle traveling in this quenched random environment. By taking the point of the view of the particle, we show that the law of its observed environment is absolutely continuous with respect to the law of the random metric, and we provide an explicit form for its Radon-Nikodym derivative. We use this result to prove a "local Markov property" along an unbounded geodesic, demonstrating that it eventually encounters any type of geometric phenomenon. We also develop in this paper some general results on conditional Gaussian measures. Our Main Theorem states that a geodesic chosen with random initial conditions (chosen independently of the metric) is almost surely not minimizing. To demonstrate this, we show that a minimizing geodesic is guaranteed to eventually pass over a certain "bump surface," which locally has constant positive curvature. By using Jacobi fields, we show that this is sufficient to destabilize the minimizing property.Comment: 55 pages. Supplementary material at arXiv:1206.494

    Thermophoresis of Brownian particles driven by coloured noise

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    The Brownian motion of microscopic particles is driven by the collisions with the molecules of the surrounding fluid. The noise associated with these collisions is not white, but coloured due, e.g., to the presence of hydrodynamic memory. The noise characteristic time scale is typically of the same order as the time over which the particle's kinetic energy is lost due to friction (inertial time scale). We demonstrate theoretically that, in the presence of a temperature gradient, the interplay between these two characteristic time scales can have measurable consequences on the particle long-time behaviour. Using homogenization theory, we analyse the infinitesimal generator of the stochastic differential equation describing the system in the limit where the two characteristic times are taken to zero; from this generator, we derive the thermophoretic transport coefficient, which, we find, can vary in both magnitude and sign, as observed in experiments. Furthermore, studying the long-term stationary particle distribution, we show that particles can accumulate towards the colder (positive thermophoresis) or the warmer (negative thermophoresis) regions depending on the dependence of their physical parameters and, in particular, their mobility on the temperature.Comment: 9 pages, 4 figure

    Ιστορική και πολεοδομική εξέλιξη της πόλης του Βερολίνου - Συγκριτική μελέτη αναβάθμισης υποβαθμισμένων περιοχών σε Αθήνα και Βερολίνο

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    130 σ.Αντικείμενο της διπλωματικής εργασίας είναι η ιστορική αναδρομή και πολεοδομική εξέλιξη της πόλης του Βερολίνου από την ίδρυσή της μέχρι σήμερα, όπως και η σύγκριση δύο πρώην υποβαθμισμένων περιοχών που αναβαθμίστηκαν τις τελευταίες δύο δεκαετίες, σε Βερολίνο και Αθήνα αντίστοιχα. Η περιγραφή αυτή έχει ως σκοπό την παρουσίαση της σπουδαιότητας και του ρόλου του Βερολίνου δια μέσου των αιώνων, την επισήμανση των πολιτικών, νομοθετικών και πολεοδομικών γεγονότων και εξελίξεων που έπαιξαν σημαντικό ρόλο στην πορεία του, καθώς και τον εντοπισμό ομοιοτήτων και διαφορών από την ανάλυση της σύγκρισης των δύο περιοχών μελέτης. Η παρούσα διπλωματική εργασία αποτελείται από έξι κεφάλαια. Στο Κεφάλαιο 1 δίνονται γενικές πληροφορίες για το Βερολίνο, περιγράφοντας τη γεωγραφική θέση και έκταση, το κλίμα, τον πληθυσμό, τα δημογραφικά στοιχεία και την διοικητική διαίρεση της πόλης. Στο Κεφάλαιο 2 παρουσιάζεται η ιστορική αναδρομή του Βερολίνου από την ίδρυση του το 1237 μέχρι και σήμερα, επισημαίνοντας τα σημαντικότερα ιστορικά γεγονότα. Στο Κεφάλαιο 3 αναλύονται πολεοδομικά σχέδια (Σχέδια Χρήσης Γης), που έπαιξαν σημαντικό ρόλο στην εξέλιξη του Βερολίνου, ως προς τον σκοπό, το περιεχόμενο και τις επιπτώσεις τους, περιγράφοντας παράλληλα την πολιτική, νομοθετική και πολεοδομική εξέλιξη της πόλης. Στο Κεφάλαιο 4 εξετάζεται η αναβάθμιση της περιοχή μελέτης Warschauer Straße του Βερολίνου. Στο Κεφάλαιο 5 εξετάζεται η αναβάθμιση της περιοχής μελέτης του Γκαζιού της Αθήνας. Στο Κεφάλαιο 6 περιλαμβάνονται τα συμπεράσματα και τα αποτελέσματα της σύγκρισης των δύο περιοχών μελέτης.Subject of the thesis is the historical overview and urban development of the city of Berlin from its foundation until today, as well as the comparison of two formerly degraded areas that have been upgraded over the past two decades, in Berlin and Athens respectively. This description is intended to show the importance and role of Berlin through the ages, highlight political, legislative and planning events and developments that played an important role in its course, and identify similarities and differences from the comparison analysis of the two study areas. This thesis consists of six chapters. Chapter 1 contains general information about Berlin, describing the geographical location and area, climate, population, demographics and administrative division of the city. Chapter 2 presents the historical overview of Berlin from its founding in 1237 until today, highlighting the most important historical events. In Chapter 3 we continue with the analysis of the aim, the contents, and the impact of urban plans (Land Use Plans), which played an important role in the evolution of Berlin, while describing the political, legislative and urban development of the city. Chapter 4 examines the upgrade of the study area Warschauer Straße, Berlin. Chapter 5 examines the upgrade of the study area of Gazi, Athens. Chapter 6 gives the conclusions and results of the comparison of the two study areas.Βασίλειος Σ. Βλάχο

    Recent Decisions

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    A Synopsis of The Tabanidae of Nebraska with a Description of a New Species from Colorado

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    Recently, the writer has had occasion to prepare a synopsis of the species of Tabanidae, otherwise known as horseflies, deerflies or gadflies, of the State of Nebraska. These flies are of importance to the farmer and stock raiser because of their blood-sucking propensities and their annoyance to stock. They breed in marshy lands and wet soil. This synopsis is based altogether on specimens collected in Nebraska and now actually present in the University of Nebraska collection. It is not probable, therefore, that it is a complete list. More extensive collecting over the state would probably reveal the presence of other species, since very little time has been spent in especially collecting these insects. The classification of Hine has been followed in the main, but in listing the species those that are closely related have been brought together. The writer is indebted to Professors Myron H. Swenk and R. W. Dawson of the University of Nebraska, who have made possible the preparation of this paper. Acknowledgement should also be made to the works of Professor James S. Hine and Baron C. R. Osten Sacken on the Tabanidae, since these have contributed greatly toward the satisfactory identification of the species and the synoptic work

    Towards a Complex, Active, Human-Centered Subject Grounded in the Sociopolitical: A Symbiosis of Edmund Husserl and Michael Foucalt

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    This thesis responds to the questions With the empirical, \u27found\u27 world prevalent as the paradigm for all valid knowledge, what happened to the relevance of the human in knowledge? Is there an alternative that does not divorce the knower from the knowing? The ideas of Edmund Husserl (1859-1938) and Michel Foucault (1926-1984), two thinkers traditionally viewed as rivals in continental philosophy and social theory, animate these questions. Both philosophers critique the taken-for-granted aspects of the world: Husserl through the constituting subject and Foucault through the socially, linguistically, and historically constituted subject. Rather than an either-or that oversimplifies the subject, a dialogue and a symbiosis between these two thinkers point to the foundation of an active, meaning-endowing subject in which this subject is enmeshed in inter-subjective power relations and in which certain knowledges are subjugated to others. Through a combined critique, it is possible to continue an investigation beyond a discursive level, to desediment more layers of knowledge, and to continue to critique the always-already there in order to understand enduring constitutions and the subject\u27s becoming

    Calculations of the Knight Shift Anomalies in Heavy Electron Materials

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    We have studied the Knight shift K(r,T)K(\vec r, T) and magnetic susceptibility χ(T)\chi(T) of heavy electron materials, modeled by the infinite U Anderson model with the NCA method. A systematic study of K(r,T)K(\vec r, T) and χ(T)\chi(T) for different Kondo temperatures T0T_0 (which depends on the hybridization width Γ\Gamma) shows a low temperature anomaly (nonlinear relation between KK and χ\chi) which increases as the Kondo temperature T0T_0 and distance rr increase. We carried out an incoherent lattice sum by adding the K(r)K(\vec r) of a few hundred shells of rare earth atoms around a nucleus and compare the numerically calculated results with the experimental results. For CeSn_3, which is a concentrated heavy electron material, both the ^{119}Sn NMR Knight shift and positive muon Knight shift are studied. Also, lattice coherence effects by conduction electron scattering at every rare earth site are included using the average-T matrix approximation. Also NMR Knight shifts for YbCuAl and the proposed quadrupolar Kondo alloy Y_{0.8}U_{0.2}Pd_{3} are studied.Comment: 31 pages of RevTex, 22 Postscript figures, submmitted to PRB, some figures are delete

    Primary vs. Secondary Antibody Deficiency: Clinical Features and Infection Outcomes of Immunoglobulin Replacement

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    <div><p>Secondary antibody deficiency can occur as a result of haematological malignancies or certain medications, but not much is known about the clinical and immunological features of this group of patients as a whole. Here we describe a cohort of 167 patients with primary or secondary antibody deficiencies on immunoglobulin (Ig)-replacement treatment. The demographics, causes of immunodeficiency, diagnostic delay, clinical and laboratory features, and infection frequency were analysed retrospectively. Chemotherapy for B cell lymphoma and the use of Rituximab, corticosteroids or immunosuppressive medications were the most common causes of secondary antibody deficiency in this cohort. There was no difference in diagnostic delay or bronchiectasis between primary and secondary antibody deficiency patients, and both groups experienced disorders associated with immune dysregulation. Secondary antibody deficiency patients had similar baseline levels of serum IgG, but higher IgM and IgA, and a higher frequency of switched memory B cells than primary antibody deficiency patients. Serious and non-serious infections before and after Ig-replacement were also compared in both groups. Although secondary antibody deficiency patients had more serious infections before initiation of Ig-replacement, treatment resulted in a significant reduction of serious and non-serious infections in both primary and secondary antibody deficiency patients. Patients with secondary antibody deficiency experience similar delays in diagnosis as primary antibody deficiency patients and can also benefit from immunoglobulin-replacement treatment.</p></div
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